Improving bone health in prostate cancer patients starting androgen deprivation therapy: does Fracture Risk Assessment Tool (FRAX®) enhance stratification and targeted management?

Abstract

Long-term use of androgen deprivation therapy (ADT) in prostate cancer patients results in increased bone turnover and decreased bone mineral density (BMD). Proper assessment of any existing osteoporotic fracture risk is crucial prior to starting treatment. However, this risk assessment is poorly performed in these patients in spite of available validated tools including the Fracture Risk Assessment Tool (FRAX®). The objective of this study was to assess the distribution of osteoporotic fracture risk in a cohort of men commencing ADT for prostate cancer using the FRAX® algorithm. Between July 2020 and May 2022, 200 men filled in the FRAX® questionnaire just before ADT. They were stratified into the high-risk (> 20% probability of a MOF over the next 10years), intermediate-, and low-risk categories for fragility fractures. We also measured their serum vitamin D and calcium levels. The average age was 73.5years (54-89). It took less than 10min to complete the assessment. Only six patients were at high-risk, were started on bisphosphonates immediately, and referred for a dual energy X-ray absorptiometry (DEXA) scan. Twelve patients in the intermediate-risk category were referred for DEXA scans for bone mineral density measurements. A total of 182 patients (91%), were in the low-risk category and given lifestyle advice only. All had normal calcium levels but 134 (67%) patients, mostly in the low-risk category, had reduced vitamin D levels (< 50nmol/L). The FRAX® questionnaire is simple and immediately identifies patients who are at risk of fragility fractures. Our study has demonstrated that the majority of men (91%) in our cohort commencing ADT for prostate cancer were considered low risk for future osteoporotic fracture. We were surprised that more than half of our patients had low vitamin D levels.